Except for the fact that OKW is the oldest, and SSR is the newest one you can stay at, they were a lot alike, at least in my eyes. There are villas in many separate buildings, neither is attached to another resort.
Depending on the circumstances, I wouldn't mind staying at OKW, but prefer Boardwalk-it's my "home", and I love the convenience of walking to MGM and Epcot. However, the ability to park right outside the building where you are staying has a certain appeal, especially if you get a villa at the BWV that is at the end of the very long hallway!
I personally prefer the Boardwalk, but the last 2 trips were more "spur-of-the-moment" so we stayed at OKW and SSR. Enjoyed both stays.